1. Field of the Invention
The invention relates to a delivery unit, in particular for feeding fuel or washing liquid in a motor vehicle, having a pump which is driven by an electric motor and has vanes, the electric motor having a rotor and a stator and the vanes being arranged on the rotor and being provided for movement in a fixed pump channel.
2. Description of the Related Art
Such delivery units are frequently used in modern motor vehicles as a fuel, pump or as a washing-liquid-pump for a window-cleaning installation and are thus known. The rotor of the electric motor is of the electric motor is of cylindrical configuration. The vanes are arranged on one of the end sides of the rotor. A housing of the electric motor serves, at the same time, as a housing for the pump and, in its region adjacent to the vanes, forms the pump channel. For the purpose of cooling the electric motor, the liquid fed is then guided through the electric motor between the rotor and a stator. The delivery unit thus comprises a very small number of components and can therefore be assembled cost-effectively.
The disadvantage of the known delivery unit is that it has very large dimensions. For example, as a result of the vanes being arranged on the end side of the rotor, the delivery unit has a particularly long axial extent.
It would be conceivable for the rotor to be of tubular configuration and the vanes to be provided on the inner wall of the rotor. However, this means that the rotor is a complicated component, with the result that it would require particularly high production costs.
The problem on which the invention is based is to configure a delivery unit of the type mentioned in the introduction such that it has the smallest possible dimensions and can be produced particularly cost-effectively.
This problem is solved according to the invention in that the stator forms at least part of the wall of the pump channel.
This configuration means that the vanes are arranged in a region of the rotor which is located opposite the stator. As a result, the delivery unit according to the invention does not require any pump-housing part designed as a pump channel and therefore has particularly small dimensions. The vanes are arranged on an easily accessible, outer region of the rotor, as a result of which the delivery unit according to the invention can be produced particularly cost-effectively.
In a delivery unit in the case of which the rotor is of cylindrical configuration, it would be possible to arrange, for example, a plurality of individual vanes on the lateral surface of the rotor. However, according to an advantageous development of the invention, the vanes produce particularly low levels of turbulence in the liquid which is to be fed if the vanes are of helical configuration. By virtue of this configuration, the liquid which is to be fed is guided by the vanes in a uniform manner, and thus free of turbulence. This turbulence-free feed is important in the case of hot fuel in particular because the latter tends to form gas bubbles. Gas bubbles in the liquid which is to be fed often result in a vast reduction in the feeding capacity of the delivery pump.
In a delivery unit in the case of which the rotor and the stator are of disk-shaped configuration, the liquid which is to be fed can be fed with particularly low levels of turbulence, according to another advantageous development of the invention, if the vanes are of spiral configuration.
The delivery unit according to the invention has a particularly high feeding capacity, along with particularly small dimensions, if, in relation to the vanes of the rotor, the stator has vanes arranged in the opposite direction.
The vanes have a particularly low weight, and thus a low mass moment of inertia, if the vanes are produced from plastic. This allows the electric motor to have a particularly low output. This results in a further reduction in the dimensions of the delivery unit according to the invention.
In order further to reduce the production costs of the delivery unit according to the invention, it is helpful if the vanes are produced integrally with the rotor or the stator. In the most favorable case, this only results in the production costs of the delivery unit according to the invention being increased to a very slight extent, since the rotor and the stator are cast with a synthetic resin anyway.
The delivery unit according to the invention comprises a particularly small number of components and can thus be assembled cost-effectively if the vanes of the stator are made in a permanent magnet of the stator.
According to another advantageous development of the invention, the vanes have a high level of stability if the vanes have a rectangular cross section.
According to another advantageous development of the invention, the vanes have a particularly low volume, and thus low material costs, if the vanes have a triangular cross section.
The invention allows numerous embodiments. In order to clarify basic principles of the invention further, two of these embodiments are described hereinbelow and illustrated in the drawing, in which: